Lisex 0.0 development contributions were the following ones:

• Team training and learning

• Fine tune of techniques and tools applied (Coq, functional testing based on formal specifications, etc.)

• Deep understanding of the MLS mechanism and its fundamentals

The last point deserves special attention. MLS advantages are as known as their disadvantages. Multi-level security is perhaps the only one model powerful enough as to present an adequate level of resistance to confidentiality attacks performed by Trojan horses. However, standard implementations have one or two defects: either they loose compatibility with applications software or it is cumbersome (or even impossible) to do standard system tasks due to the restrictions enforced by the system. Any of these features render MLS systems as a commercial option.

We had the chance to experiment with Lisex security model and prototype. This allowed us to uncover most of the conceptual causes that make traditional MLS implementations unsatisfactory. Moreover, a solution has been developed for each of these problems. These solutions will be the basis of GIDIS Trusted Linux. Hence, GIDIS Trusted Linux will feature all advantages of MLS systems but none of their disadvantages at a reasonable performance cost.